Ring-width and blue-light chronologies of Podocarpus lawrencei from southeastern mainland Australia reveal a regional climate signal

Publication Name

Climate of the Past

Abstract

High-resolution palaeoclimate proxies are fundamental to our understanding of the diverse climatic history of the Australian mainland, particularly given the deficiency in instrumental datasets spanning more than a century. Annually resolved, tree-ring-based proxies play a unique role in addressing limitations in our knowledge of interannual to multi-decadal temperature and hydroclimatic variability prior to the instrumental period. Here we present cross-dated ring-width (RW) and minimum blue-intensity (BI) chronologies spanning 70 years (1929-1998) for Podocarpus lawrencei Hook.f., the Australian mainland's only alpine conifer, based on nine full-disc cross-sections from Mount Loch in the Victorian Alps. Correlations with climate variables from observation stations and gridded data across the 1929-1998 period reveal a significant positive relationship between RW and mean monthly maximum temperatures in winter throughout central Victoria (rCombining double low line0.62, p<0.001) and a significant negative correlation to winter precipitation (rCombining double low line-0.51, p<0.001). We also found significant negative correlations between RW and monthly snow depth at Spencer Creek in New South Wales (rCombining double low line-0.60, p<0.001). Of the assessed BI parameters, delta blue intensity ( "BI; the difference between early- and late-wood BI) displayed the greatest sensitivity to climate, with robust spatial correlations with mean October to December maximum and minimum monthly temperatures (rCombining double low line-0.43, p<0.001; rCombining double low line-0.51, p<0.001) and July precipitation (rCombining double low line0.44, p<0.001), across large areas of northern Victoria. These promising findings highlight the utility of this species for future work. With the very limited availability of suitable long-lived and cross-datable species on the Australian mainland, these results have significant implications for advancing high-resolution palaeoclimate science in southeastern Australia and for improving our understanding of past climate in the region.

Open Access Status

This publication may be available as open access

Volume

18

Issue

12

First Page

2567

Last Page

2581

Funding Number

SR200100005

Funding Sponsor

Australian Research Council

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Link to publisher version (DOI)

http://dx.doi.org/10.5194/cp-18-2567-2022